Add missing Doxygen groups to new APIs.

Doxygen docs only appear on DAC if they are a part of a group.

Test: None
Bug: http://b/130659204
Change-Id: I7617c10a04de0fde7fbd1213f1fe6dd0d22208bd
diff --git a/include/android/font_matcher.h b/include/android/font_matcher.h
index ad5a4da..e286a4c 100644
--- a/include/android/font_matcher.h
+++ b/include/android/font_matcher.h
@@ -15,6 +15,11 @@
  */
 
 /**
+ * @addtogroup Font
+ * {
+ */
+
+/**
  * @file font_matcher.h
  * @brief Provides the font matching logic with various inputs.
  *
@@ -205,3 +210,5 @@
 __END_DECLS
 
 #endif // ANDROID_FONT_MATCHER_H
+
+/** @} */